Packaging made of flushable multilayer films is known in the prior art, where the layers of said films have different solubility in water. If humidity and temperature are excessive, or if an excessively high level of contact moisture is present, e.g. moisture from the hand, the external surface layer which has lower water-solubility in these known films tends to block and (to some extent) to dissolve, and consequently the layer which is located thereunder and which is protected by the surface layer and which has better water solubility is attacked, with resultant premature breakdown of the layer composite. Films of this type therefore have only limited shelf life and certain precautionary measures are required when handling them, for example use of gloves.
EP 0 613 362 B1 attempts to solve said problem by producing a two-layer film which is resistant to ambient moisture, and the respective layers of which have different solubility in water. One of the layers is composed of cold-water-soluble polyvinyl alcohol and can be dissolved completely within one minute by stirring in water. The other layer is composed of hot-water-soluble polyvinyl alcohol, and can be dissolved under said conditions but only with a delay so great that it is classified as non-flushable for the purposes of the present invention.
However, there is a need for multilayer films which are relatively resistant to ambient moisture but at least water-flushable. In particular, there is a need for flushable packaging made of multilayer films of this type which, on water-flushing, e.g. toilet-flushing, do not cause blockages in outflows or in drainage or sewer pipes.
It was therefore an object of the present invention to provide a flushable multilayer film which is relatively resistant to ambient moisture, and a corresponding flushable packaging material and, respectively, packaging for a very wide variety of applications, made of said multilayer film.